<wfs:GetFeature
        xmlns:ogc="http://www.opengis.net/ogc"
        xmlns:st_gml31="http://www.stations_gml31.org/1.0"
        xmlns:ms_gml31="http://www.measurements_gml31.org/1.0"
        xmlns:wfs="http://www.opengis.net/wfs"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://www.opengis.net/wfs http://schemas.opengis.net/wfs/1.1.0/wfs.xsd">
    <wfs:Query typeName="st_gml31:Station_gml31">
        <ogc:Filter>
            <ogc:PropertyIsEqualTo>
                <ogc:PropertyName>
                    st_gml31:Station_gml31/st_gml31:tag/@st_gml31:code
                </ogc:PropertyName>
                <ogc:Literal>3</ogc:Literal>
            </ogc:PropertyIsEqualTo>
        </ogc:Filter>
    </wfs:Query>
</wfs:GetFeature>